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A brief description of a reciprocating device includes a basic door closer system which comprises a spring operated device controlled with liquid or gas. The device typically contains a piston assembly including a piston and sealing o-ring; piston rod varieties which include curved and non-curved surfaces; internal compression spring and hydraulic biasing operators; cylindrical-piston tube; sealed and non-sealed end caps; fluid restriction valves; attachment members; and the checking mechanism to which this invention pertains. Such door closer systems which comprise checking mechanisms are described in U.S. Pat. Nos. 2,732,920; 2,920,338; 3,032,806; 3,162,889; 3,566,435; 3,665,549; 4,777,698; and Canadian Pat. No. 623,038.
The checking mechanism is utilized to independently hold the door and door closer in an open or extended position for an indefinite period of time. The simplistic mechanism is axially mounted upon the extended rod of the device, for leveraging certain biasing forces controlled by the device into torsion. The torsion is urged between opposing points within an axial plane of the mechanism. The torsion causes substantial direct frictional pressure onto the surfaces of the piston rod. Thus, the mechanism frictionally checks the reciprocative function of the device with direct pressure causing the friction. Among the more elaborate checking mechanisms developed are illustrated in U.S. Pat. No. 4,194,264 to Soffregen (1980), and U.S. Pat. No. 4,815,163 to Simmons (1989). Through variously attached apparati comprising these mechanisms, an elaborate method is created to check the rod of the device similarly to the basic mechanism disclosed herein.
The prior art checking mechanism is usually metal stamped from a sheet material such as a predetermined sheet metal gauge. The mechanism comprises three main components: a) an aperture configuration bounded within a central structure; b) a trigger appendage; and c) a fixated joint connecting component a onto component b. The aperture configuration permits the mechanism to mount upon the rod of the device. The aperture configuration comprises opposing loci which define the opposing friction points. These points create the torsional pressure causing the friction within the axial plane. The central structure provides a boundary for the aperture configuration. The trigger appendage acts as a lever and provides a trigger point for abutment to the piston body. The central structure and the trigger appendage are typically flattened planes composed from the sheet metal gauge. The fixated joint angularly attaches the central structure onto the trigger appendage. The components differ slightly on the various prior art mechanisms, relative to the independent manufacturer's own design. However, the functionality of the three components are similar on most the prior art mechanisms.
The hold-open feature is manually activated by first opening the door to a desired position, thus extending the piston rod of the fixated door closer system from within the piston body. A counter-force is then normally created as a result of the system's biasing operators. The checking mechanism is axially mounted onto the rod through the aperture configuration, first by moving the mechanism to a desired position on the extended rod. Releasing the door, the biasing operators act to return the rod towards the normally retracted position within the body. The biasing force causes the mechanism to lever at the trigger appendage, once the body contacts the mechanism upon the trigger point.
The biasing force is redirected at the fixated joint which causes the checking mechanism to torsionally pivot on the center axis of the aperture configuration, and pivot on the axis of the piston rod. Thus, the mechanism pivotally engages onto the rod surface, urged upon the metallic edges of the opposing loci comprising the opposing friction points. The energy is substantially equalized and distributed to the points which interact and deliver the friction within the axial plane of the mechanism. The direct frictional pressure created by the points is applied onto the curved and non-curved surfaces of the piston rod, whereby the mechanism frictionally checks the device. More biasing force controlled by the device results in more torsional pressure causing the friction onto the surfaces of the rod. Sectionally dividing the mechanism through the common axis of symmetry and connecting the opposing points within the axial plane, connected to the trigger point, a simple angle is illustrated. Therefore, the reader can better understand the principles of pressure distribution, and the distance from the trigger point to the opposing loci comprising the opposing friction points.
Component a) the aperture configuration is not a primary embodiment of this divisional invention. However, full disclosure can be learned within the parent application.
Component b) the trigger appendage acts as a lever to leverage the mechanism for pivotal engagement upon the device. The trigger appendage transposes the biasing forces controlled by the device into the direct frictional pressure upon the rod. The trigger appendage provides a trigger point for abutment onto the piston body. The trigger point varies upon the surface of the trigger appendage. The trigger point is defined upon a trigger plane. The trigger plane generally projects from the origin axis for the fixated joint, projected to the trigger point abutting the body of the device. Because the surface of the trigger appendage is substantially flat and also projects from the origin axis, the trigger plane therefore remains fixated as the trigger point varies upon the surface of the trigger appendage. Thus, in prior art the trigger point is best defined upon a non-variable trigger plane. The flat surface of the trigger appendage offers no other adjustable features for the varying trigger point.
Prior art checking mechanism provide a substantially similar distance between the three functional points of leverage. Specifically, the distance from the trigger point to the fulcrum locus is not much greater than the distance between the opposing friction points within the loci. An average door closer system comprising a 1.25" (32 mm) piston body and 0.313" (8 mm) piston rod, comprises a 1.5-to-1 average leverage ratio for the mechanism. Again, unless the piston rod is modified, the distance between the two opposing points can not be modified. Resultantly, the sectional distance between the two opposing points may never become altered or decreased to partake in any possible leverage advantage for the trigger point.
It may seem obvious that to obtain an increase in leverage ratio, the length of the trigger appendage should therefore be increased. However, merely increasing the length of the fixated trigger appendage would require decreasing the fixated joint, because of the flattened nature comprising the trigger appendage. The flattened surface of the trigger appendage limits the trigger point to the non-variable trigger plane, and will not compensate for an increase in the surface area resulting from any lengthening of the trigger appendage. Lengthening the trigger appendage would also place more stress onto the joint, further weakening the mechanism which often does not comprise hardness or temper modification for the soft sheet steel gauge.
The trigger appendage must create a functional gap between the central structure and the piston body. The gap must prevent any simultaneous touching of the central structure against the body, which disrupts the direct frictional pressure created by the opposing points upon the rod. The flattened trigger appendage also offers less surface area to increase the functional gap. As the checking mechanism wears and fatigues, the trigger point changes and climbs the surface of the flattened trigger appendage. Due to the non-variable trigger plane, the functional gap is reduced at the same rate as the climbing trigger point. Thus, there is less surface for the trigger appendage to provide certain variable extension and adjustment for a wearing checking mechanism. The flattened trigger appendage also offers less universalness to adapt a single checking mechanism to various devices.
Component c) the fixated joint comprises an angular connection between the central structure and the trigger appendage. The joint angularly directs the biasing forces controlled by the door closer biasing operators, to the opposing points torquing within the axial plane which cause the direct frictional pressure. All prior art checking mechanisms disclosed demonstrate a fixated joint which is greater than 90 degrees at the origin for both components. Some modern checking mechanisms comprise angular fixated joints as great as 120 degrees at the origin. The angle at the origin is determined by projecting an axis (face axis) upon the face of the central structure, and projecting the other axis (origin axis) from the origin for the trigger appendage. The origin may be determined as the best angle created between both components.
Among other factors, the angle must limit the central structure from simultaneously touching against the piston body along with the trigger point. Any simultaneous touching of the central structure disrupts the torsional engagement between the opposing friction points urged upon the rod. Therefore, the degree of the angle for the fixated joint must contribute to the functional gap between the central structure and the piston body. Because the prior art mechanisms are primarily manufactured from common sheet steel which is relatively soft, the joint is therefore subject to fatiguing which reduces the functional gap. In order to provide a mechanism which does not slip, the joint should be both fixated and capable of withstanding sufficient pressure. U.S. Pat. No. 3,566,435 to Nakamura (1971) shows a perpendicular angular joint which is not fixated. Resultantly, this mechanism provides an intentional slipping feature as described within the contents of the patent.
Another known problem contributing to a substantial reduction in the functional gap is defined by the natural wearing of the metallic edges which comprise the opposing friction points. The wearing causes the points to flatten which may result in a loss of substantial direct frictional pressure. Thus, the pressure becomes distributed over the two flattened points instead of being forcefully urged, as upon sharper biting edges comprising the loci of a branch new checking mechanism. A decrease in the functional gap may also be caused by the lateral rotation of the mechanism as previously described. Conclusively, any substantial reduction in the functional gap may ultimately render the mechanism useless.
Consider the results of a pressure test conducted on a prior art checking mechanism manufactured from 12 gauge sheet steel, comprising a flattened central structure; a flattened trigger appendage comprising the trigger point upon a non-variable plane projecting from the origin axis; and an fixated joint of approximately 120 degrees. The specimen checking mechanism was mounted to check a modern door closer comprising a 1.25" diameter piston body, with a 0.3125" diameter piston rod. With only the pressure created by the door closer biasing means, after pivotal engagement the average measurable functional gap between the central structure to end cap of the piston body was approximately 0.068". At 50 lbs. of direct pressure placed upon the end of the door closer rod, the fixated joint began fatiguing and widened, and the functional gap was reduced to 0.035". At 115 lbs. of direct pressure, the fixated joint had sufficiently fatigued to reduce the functional gap to 0.000", causing the central structure to simultaneously contact the piston body along with the trigger point area.
The results of this test concluded that an increase in the pivotal engagement substantially eliminated the functional gap between the central structure and the end cap, thus canceling the trigger mechanism and causing the checking mechanism to completely fail. Thus, it seems obvious that prior art checking mechanisms would benefit by moving the central structure away from the piston body to increase the functional gap. This could be achieved by decreasing the fixated joint to less than 90 degrees at the origin, thus raising the trigger area upon the non-variable plane of the flattened surface comprising the trigger appendage. The foregoing would increase the described functional gap, and increase the life of the checking mechanism. Tempering, hardening, and further modifying the joint with crimping, could create a mechanism capable of withstanding a greater pressure.